(CNN) -- A fourth person has died, a day after a lumber plant employee shot several people at his company's factory near Lucerne, Switzerland.

The shooter killed himself and two other people Wednesday, and one of seven other people wounded in the incident died Thursday morning, according to Lucerne county police spokesman Urs Wigger.

Police have not yet named any of the victims, and they had no update Thursday on how the other six people were faring.

The murder weapon was a Sphinx AT-380 handgun -- not a military-issued weapon -- Wigger said, adding that police were investigating how the shooter got the gun, and whether he had it legally.

The gunman, 42, was a long-time employee of Kronospan, a wood panel manufacturer in the village of Menznau, about 30 kilometers (19 miles) outside Lucerne, police said.

The factory employs 350 people, according to a Lucerne-based newspaper.

It's unclear why the gunman opened fire as employees were taking a morning break.

Local media reports suggest the plant has had to cut production because of a reduction in the timber harvest.

A statement posted in five languages on Kronospan's Swiss website on Wednesday read: "It is with tremendous sadness that we must confirm that there has been a shooting incident at our factory this morning, resulting in multiple serious injuries and fatalities. The shock and grief at Kronospan is not possible to put into words."

The posting also included a hotline number for employees. That hotline has been "widely used," according to police.

Representatives for the company's U.S. and UK branches said they had limited information about what happened and offered their condolences.

"It's a terrible tragedy, and our thoughts are with the families of the people who have lost their lives," the UK spokesman said.

"We, too, are deeply saddened by this tragic event, and our thoughts are with our Swiss colleagues and the families of those involved," said the U.S. spokeswoman.

The Menznau Kronospan factory, which makes wood products under the brand name Kronoswiss, is one of 10 plants in seven countries run by the Swiss Krono Group, according to the company's website.

Its U.S. subsidiary, Kronotex USA, says on its website that the company has been a family business since its inception in 1897 in Austria, and its total annual sales exceed $1 billion.

CNN's Fred Pleitgen, Saskya Vandoorne and Carol Jordan contributed to this report. CNN's Laura Spark-Smith wrote from London, and Mark Morgenstein and Ben Brumfield wrote from Atlanta.